//frameworks/base/cmds/wm/src/com/android/commands/wm/Wm.java

IWindowManager mWm = IWindowManager.Stub.asInterface(ServiceManager.checkService(
                        Context.WINDOW_SERVICE));

Point initialSize = new Point();
Point baseSize = new Point();
mWm.getInitialDisplaySize(Display.DEFAULT_DISPLAY, initialSize); //Get true size
mWm.getBaseDisplaySize(Display.DEFAULT_DISPLAY, baseSize); //Get current size

mWm.setForcedDisplaySize(Display.DEFAULT_DISPLAY, w, h); //Set to custom size
mWm.clearForcedDisplaySize(Display.DEFAULT_DISPLAY); //Reset to true size

1440*2560
1080*1920
720*1280